The LDP won last week's elections in Japan. Shinzo Abe is the new prime minister and has promised to reverse the previous government's stance on nuclear power. The LDP is pro-nuclear and has indicated that the nuclear power plants in Japan will be started up again. More interesting is what will happen to nuclear energy research in Japan in the aftermath of Fukushima. Could it be an opportunity to investigate safer nuclear technologies, such as molten salt reactors ? The late Dr. Furukawa was a big proponent of MSR's inside and outside Japan. Furthermore, China, a strategic rival of Japan, is investing in molten salt reactor technology. Are MSRs really a better alternative than other reactor types such as LWRs, in a country which cares about earthquakes and tsunami's ?

It is such a waste to give up nuclear energy, which produced a third of Japan's power just because a few of older reactors were damaged due to unprecedented earthquake and tsunami in living history. Japanese are too knowledgeable for sense not to prevail in due course.If the geological fault lines or vulnerability to earthquakes or tsunami limit the sites, They could also build floating power plants and anchor them where required. Russians have already made a start.The Japanese have a lot of Plutonium from reprocessing in France/UK/Japan. They could set up uranium/thorium breeders using it as fuel as originally planned. They have already done a lot of R&D. After bad experience with sodium as coolant, they could shift to lead or salt instead of just giving up.

Shinzo Abe endorses nuclear power and hints at reactors which will be "completely different from those at the Fukushima Daiichi nuclear power plant". What could he have in mind ?

The Japanese have had a major sodium fast reactor program for some time. Results from the MONJU were very poor, but he could be talking about the newer passively safe pool type or hybrid loop/pool type sodium fast reactors.

The latest BWRs offered by Japanese heavy industrial companies are also passively safe (have full decay heat shutdown cooling even in full station blackout). ABWR-II, Toshiba's EU-ABWR, GE's ESBWR and the French BWR design Kerena (formerly SWR1000) all have shutdown cooling systems that don't need electricity.

My guess that eithere these passive SFRs or passive BWRs are meant by Shinzo Abe. Probably not MSRs, the Japanese have not done much work here.

According to the document, Japan had about 47 tons of plutonium as of the end of 2016, down 1 ton from a year before thanks to the start of two reactors that use MOX fuel. Even so, the amount is said to be enough to make thousands of nuclear bombs.

Thorium reactors would be a much faster and more effective way for Japan to reduce its plutonium stockpile. When you consume plutonium in the presence of uranium in a nuclear reactor, you just make more plutonium.

According to the document, Japan had about 47 tons of plutonium as of the end of 2016, down 1 ton from a year before thanks to the start of two reactors that use MOX fuel. Even so, the amount is said to be enough to make thousands of nuclear bombs.

Thorium reactors would be a much faster and more effective way for Japan to reduce its plutonium stockpile. When you consume plutonium in the presence of uranium in a nuclear reactor, you just make more plutonium.

Mr. Sorensen,I have little doubt that the people implementing this plan also know what you know, that this will not reduce the plutonium stockpile any. They have a requirement, either self imposed or imposed by treaty, to have a non-weapon use for their plutonium stock. Without a reactor to burn plutonium they'd have to dispose of this valuable material in some other way. What would those means of disposal be? Exporting it seems most likely. Then they'd have to find someone willing to buy it, someone that won't just buy it from them to later drop it on their heads.

Perhaps they have read your papers and see this as a transition to a thorium cycle. Maybe they see this as a way to create a sustainable plutonium fuel cycle. Japan has been investigating ways to extract uranium from seawater. Being an island nation they don't have a lot of choices for domestic sourced energy. As difficult and expensive uranium from seawater might be it is something that they don't have to beg another nation to get.

As the article says the details of their plans are unclear. This may be a way to quietly work their way towards a nuclear weapons program. It's not like hiding a nuclear weapons program under the veil of civilian power generation is a new thing. Japan does have a madman lighting off nuclear weapons and large rockets in their backyard. This "rocket man" might need more persuasion than a former reality TV star turned politician can provide to change his ways. A secret nuclear weapon program is not a deterrent, but a demonstration of a working nuclear weapon would be. I see this development as a means for Japan to keep their options open.

A MOX processing plant allows them to keep their plutonium without violating any rules or treaties. It lets them experiment with plutonium chemistry which can be useful in weapons manufacture and in creating a plutonium-thorium fuel cycle. They'll get energy from this stockpile in the process, without having to rely on the kindness of other nations to trade plutonium for coal or oil.

I agree that converting this plutonium to U-233 would be a better option, but can we agree that what they are doing now is at least better than most of the other options they have? This is certainly better than walking away from nuclear power like a lot of people in Japan seem to want to happen.

_________________Disclaimer: I am an engineer but not a nuclear engineer, mechanical engineer, chemical engineer, or industrial engineer. My education included electrical, computer, and software engineering.

The policy suffered another setback recently as Japan Nuclear Fuel Ltd. unveiled plans to delay by three years the completion of its spent-nuclear-fuel reprocessing plant under construction in the Aomori Prefecture village of Rokkasho. JNFL said late last year that the plant is now scheduled to be completed during the first half of fiscal 2021, beginning in April 2021, instead of during the first half of fiscal 2018 as previously planned. Construction work on the plant began in 1993, with completion initially planned for 1997. Almost 25 years later, the plant has yet to go online, despite the more than 2 trillion yen ($17.9 billion) that has already been spent.

I'm not sure what happened. I though the US was negotiating with Japan to get them to agree not to do reprocessing, but to bring them to Argonne Labs to study the topic. So now they can reprocess if they like?

The most notable feature of the pact is that it allows Japan to reprocess spent fuel from nuclear power plants to extract plutonium. But the fact that the agreement allows Japan to reprocess spent nuclear fuel should not be used by the Japanese government as a pretext for pursuing a reprocessing program. Japan already has enough plutonium to make some 6,000 atomic bombs similar to the one dropped on Nagasaki in August 1945. Japan has no plausible plan to reduce its stockpile. The nuclear reprocessing plant the Japanese power industry is building in Rokkasho, Aomori Prefecture, should not be brought online.

The only useful way to use tons of plutonium peacefully is nuclear energy. They should use it themselves or transfer to some other user.If they develop a thorium cycle using it as initial fissile feed, they could become self sufficient. A thorium furled reactor could be water cooled, avoiding their bad experience with sodium.

Since the plutonium is reactor grade, it has too much Pu240 and Pu242 to be used as a fission device. So, I would say Japan cannot make a bomb from those stockpiles. Of course, the reactor-grade plutonium could be used as a dirty bomb, but so could lead, mercury, other heavy metals and/or actinides.

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